Message: Illegal String Offset Upgrade from Codeigniter2x Version to Codeigniter 3x version - php

Question

I recently switched my project package from Codeigniter 2X version to Codeigniter 3X version.
Earlier all my code worked fine but now with new package its showing some minute errors where I am not able to run my code.
The following is the error:
Message: Illegal String Offset:
My Controller:
public function proflist(){
$data = "";
$this->load->model('feedbackmodel');
$data['teachers'] = $this->feedbackmodel->getFaculty();
$this->load->view('feedback/proflist',$data);
}
My Model:
public function getFaculty(){
$query = $this->db->query('SELECT * FROM teacher');
return $query->result_array();
}
My View:
<?php
if(!empty($teachers)) {
foreach($teachers as $y){
?>
<tr>
<td><?php echo $y->fid; ?></td>
<td><?php echo $y->fname." ". $y->lname; ?></td>
<td><?php echo $y->email; ?> </td>
<td>
...
Is there any mistake ? How shall i change it. Please let me know:) Thank You.

Answer 1

The reason for this is most likely the version of PHP you're using. Before PHP 7.1 it was only a Notice thrown for the use of an illegal offset. 7.1+ will now throw a Warning. You can avoid it by wrapping an 'if not, isset' in your controller around the offending array. Be sure to cast the array also.
You'll find a good explanation for it here.
public function proflist() {
$data = "";
$this->load->model('feedbackmodel');
$data['teachers'] = (array) $this->feedbackmodel->getFaculty();
if(!isset($data['teachers'])) {
$data['teachers'] = '';
}
$this->load->view('feedback/proflist',$data);
}
To be certain of the version of PHP you're running, you can use phpinfo();.

Answer 2

You need to be more aware of what your variable types are.
In your controller
public function proflist(){
$data = "";
$this->load->model('feedbackmodel');
$data['teachers'] = $this->feedbackmodel->getFaculty();
$this->load->view('feedback/proflist',$data);
}
You declare $data as a STRING by way of $data = "";,
Then you decide it's going to be an array by way of
$data['teachers'] = $this->feedbackmodel->getFaculty();
To be correct $data should be declared as an empty array, not an emtpy string.
public function proflist(){
$data = array(); // Using the older style of declaring an array.
$this->load->model('feedbackmodel');
$data['teachers'] = $this->feedbackmodel->getFaculty();
$this->load->view('feedback/proflist',$data);
}
Now in your Model your returned data is created via
return $query->result_array();
If you look up the codeigniter documentation on this, it will tell you that the resulting data is an Associative Array i.e $data['teachers'] will be of the form
$data['teachers']['fid'] etc.
Your View requires it to be an object.
So you can change your view which requires $teachers to be an object,from...
<?php
// $teachers should be returned from result() which is an object.
if(!empty($teachers)) {
foreach($teachers as $y){
?>
<tr>
<td><?php echo $y->fid; ?></td>
<td><?php echo $y->fname." ". $y->lname; ?></td>
<td><?php echo $y->email; ?> </td>
<td>
...
To
<?php
// $teachers is returned from result_array() which is an associative array.
if(!empty($teachers)) {
foreach($teachers as $y){
?>
<tr>
<td><?php echo $y['fid']; ?></td>
<td><?php echo $y['fname']." ". $y['name']; ?></td>
<td><?php echo $y['email']; ?> </td>
<td>
...
OR simply change the return on your model which is a one liner. So change your Model from
public function getFaculty(){
$query = $this->db->query('SELECT * FROM teacher');
return $query->result_array(); // Return an associative array
}
To
public function getFaculty(){
$query = $this->db->query('SELECT * FROM teacher');
return $query->result; // Return an object
}
So the short version is:
Check your returned array structure. You should use var_dump() for this.
Change your code to suit.
Either change the return on your model from result_array() to result() or
Change your views from addressing objects to associative arrays.
I'm pushed for time to go into any more detail at this stage, but this should help you see what is going on.